Phonograph recording machine



May 15, 1934. GENT l}958,616

PHONOGRAPH RECORDING MACHINE FiledDec. 25,1952

INVENTOR E. W. GENT 40 In the accompanying Patented May 15, 1934 UNITEDSTATES PHONOGRAPH RECORDING MACHINE Edgar W.

Gent, Morristown, N. J., assignor to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application December 23,1932, Serial No. 648,693

6 Claims.

This invention relates to phonograph recording machines and particularlyto those using the pivoted type of recorder, that is, the type whereinthe recorder is mounted upon a pivoted arm which 5 is slowly rotatedsimultaneously with the record blank to form a spiral groove thereon.

In playing a record it is desirable to place the reproducing needle inthe proper groove on the record as quickly as possible and withoutomitting any of the recorded matter. The most convenient way ofaccomplishing this is by making the first few grooves of greater pitchthan. is normally required for recording so that they will be readilyvisible and accessible. By this means the reproducing needle can be setdown over a relatively large area and still find its way quickly intothe proper groove. The difficulty in this method arises in forming alarge pitch initial groove in the record. Ordinarily this requires theequivalent of two or more recorder feed mechanisms which are almostduplicates, with special mechanisms for linking them together to makethe transition from one to the other smooth and gradual.

The object of this invention is to provide a-simple recorder feedmechanism which is-capable of imparting to the recorder a graduallydiminishinginitial velocity which becomes constant at the ve-' locityfor recording sound.

In its general form this invention comprises a recorder mounted on amovable support and driven through an intermediatemember by a devicemoving at constant speed, the intermediate memher being capable ofgiving the effect of expanding or contracting so that the distancebetween the recorder support and driving device can be varied at thebeginning of each recording thereby providing a means for changing theinitial pitch of the grooves of a record.

drawing which illustrates a preferred form of the invention, Fig. 1 is aplan view of a recorder arm and drive of the pivoted type with the rapidspiral forming mechanism incorporated thereon;

Fig. 2 is a-corresponding elevation of the recorder arm, drive andspiral forming mechanism; Fig. 3 is an enlarged view of the releasingdevice for the mechanism; and

Fig. 4 is an enlarged perspective of the feed mechanism for the recorderarm. I

Referring to the drawing, 10 is a recorder of any suitable constructionmounted on a short arm 11 which is pivotally mounted on arm 12 to permitthe recorder to be raised or lowered with respect to the record blank"13. The arm 12 is pivoted for horizontal motion at 14. About the samepivot 14 is rotatably mounted a driving arm 15 at the free end of whichis located a means for imparting uniform angular velocity to the arm. Inthe present invention this means comprises a brush 16 adapted to engagea plain spiral groove engraved in the underside of the record blanksupport 36. The individual bristles of the brush enter the groove andare driven laterally by'its walls at a speed determined by its pitch.The recorder is therefore made to out a similar groove in the recordblank.

The driving force is transmitted to the recorder 10 through pin 17 onthe brush arm 15 cooperating with cam 18 which is secured to arm 12. Theprincipal function of the cam 18, however, is not merely to drive therecorder arm 12 but to vary the distance between its axis of rotation 19and pin 17 at a predetermined rate thereby imparting to the recorder arm12 an additionalangular velocity greater than that available in brusharm 15. This additional angular velocity is utilized in forming therapid spiral groove.

In order to drive the cam 18 a spring 20 is used. The spring is wound bymeans of handles 21 secured to shaft 22 which is geared to cam 18 sothat the handles and cam rotate together. The details of the gearing arenot shown but they may be obtained from U..S. Patent No. 1,155,640 to G.Brown dated October 5, 1915. A spring 23 insures constant contactbetween pin 17 and cam 18 and thus the recorder arm 12 is returned toits starting position relative to the driving-arm 15 when the cam isrotated. A stop 24 on the recorder arm 12 prevents the cam from rotating'90 too far when the cam is forming the starting spiral and the governor25 regulates the angular velocity of the cam.

In order to record, the turntable 36 is rotated, the feed mechanism isstarted and the recorder is lowered on to the record blank. For thepurpose of this invention, any constant speed turntable drive can beused and hence for the sake of simplicity none is shown. To start thefeed mechanism, however, brush 16 must be raised and for this purpose alever 26,is provided. This lever, through link 27 and toggle 28,releases driving arm 15 which is thereby rotated about pivot 3'7 by theaction of spring 29 until the brush 16 engages the feed groovesunderneath turntable 36. Toggle 28 cooperates with a pawl 30, which isactuated by the same motion of the lever 26, and releases a ratchet 31to permit the rapid spiral forming mechanism to begin operating.Simultaneously, with therelease of ratchet" 31,

recorder 10 is lowered by the action of cam 32 which forms a part oflever 26.. The arm 11 supporting the recorder is pivoted at 33 and ismaintained in contact with cam 32 by means of its unbalanced weight sothat as lever 26 is actuated and the cam is rotated, the arm moves withit thereby permitting recorder 10 to be lowered on to the record blank.The lever 26 is provided with a leaf spring 34 to allow the recorder tomove vertically under impulses imparted to it by any undulations inthe'record surface, and a stop 35 to prevent the recorder from beinglowered too far. The spring 34 acts as a shock absorbing medium betweenvertically immovable in 35 and vertically pivoted arm 34 which contactscam 32 eccentrically to its center of rotation 38 and tends to rotate itclockwise against the pressure of spring 34.

To operate the recorder the spring 20 is wound by turning the handles 21clockwise until cam 18 permits arm 15 to strike stop 24. This requiresabout a quarter turn of the shaft 19. As shown in the drawing, thedirection of the recorder feed is from the edge of the record to thecenter and the recorder is accordingly swung over towards the edge ofthe record preparatory to cutting a groove. Next, lever 26 is pushedtothe right until the recorder arm begins to move laterally, indicatingthat brush 16 is in contact with its feed groove. Lever 2G is then moveda little more slowly in the same direction until the stylus of therecorder strikes the record blank, at which point the rapid spiralmechanism is automatically released and the stylus is seen to move quiterapidly for a short time and then to slow down to a constant recordingspeed. At this point, the

sound controlled electrical currents to be recorded can be sent throughthe recorder and the feed mechanism operated as usual until the recordis finished.

If it is desired to record a number of individual recordings on the sameblank it is possible by means of this invention to provide eachrecording with a rapid spiral starting groove. Allthat is required isthe winding of the spring 20 and the setting of the stylus over thedesired starting point of the recording. Upon advancing lever 26 asbefore, the same cycle of events occurs and the groove is again formed.The feed mechanism shown is particularly well adapted to provide astarting groove at any point on the record blank because of the largenumber of bristles in contact with the feed groove. Other feedmechanisms, such as gear and sector mechanisms can also be used, butthese do not provide as large a range of possible starting pointsbecause of the relatively small number of teeth usually employed in suchdevices.

It will be noted that the transition from the spring drive to theordinary feed is controlled by the contour of cam 18 and can be made asgradual as desired merely by suitably shaping the cam. This is a verydesirable feature since, by its 7 use, shocks to the recorder stylus dueto the cessation of the rapid spiral forming mechanism are minimized andhence extraneous noises are eliminated from the record.

What is claimed is: I 1. In a recording machine, a record blank, a

rotatable support therefor, a recorder adapted to cooperate with therecord blank, a pivoted support for the recorder, driving means for therecorder comprising a driving arm rotatable at a substantially uniformrate about the axis of rotation of the recorder support, and means forrotating the recorder support relative to the driving arm, whereby therecorder is caused to move across the record at a decreasing rate ofspeed which becomes constant when the speed ing means comprising aplurality of driving mechanisms each adapted to impart a differentmotion to the recorder.

3. Driving means for a recorder comprising two arms pivoted aboutsubstantially the same axis, one of said arms comprising the support forthe recorder, means between the arms for producing relative motiontherebetween, means for driving the free arm at a uniform rate, arelease mechanism for initiating the operation of the first mentionedmeans simultaneously with the second mentioned means whereby therecorder will be caused to move at a relatively high speed whichgradually diminishes until the uniform speed of the second driving meansis reached.

4. Driving means as in claim 3, the means between the arms for producingrelative motion therebetween being a cam and a follower.

5. A phonograph recorder comprising a record blank, a turntabletherefor, a recorder adapted to cooperate with the record blank, apivoted supporting arm for the recorder; driving means for the recordercomprising a grooved disc concentric with and secured to the turntable,a brush member cooperating with the groove disc and mitting the motionof the driving arm to therecording arm, said means comprising a platecam driven from a spring on the recorder arm and a follower on thedriving arm, whereby the speed of the. arm is augmented according to theshape of the cam. and unitary means for initiating the motion of thedriving arm, the recorder arm and cam.

6. In a recording machine a record blank, a rotatable support therefor,a recorder adapted to cooperate with the record blank, a pivoted supportfor the recorder, driving means for the recorder comprising a drivingarm rotatable at a substantially uniform rate, and means for rotatingthe recorder support relative to the driving arm whereby the recorder iscaused to move across the recorder blank at different speeds.

EDGAR W. GENT.

